Hi, I am new to this forum and have been advised to seek info and advice here from The Thyroid UK forum.
I recently discovered I was hyperthyroid with positive thyroid antibody results indicative of autoimmune thyroid disease following blood tests as feeling unwell with multiple symptoms. I was advised to have B12, Vitamin D, Folate and Ferritin levels checked as you can often be deficient in these nutrients with Thyroid disease.
I have been told B12 is low -56 (51-128)
Folate 2.2 (3.1-20.5)
Please advise what other blood tests/ results are helpful in diagnosing.
Thanks in advance.
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Blossom1573
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Pernicious Anaemia as used by the PAS is an autoimmune condition that attacks and destroys the mechanisms in the terminal ileum that is used for absorbing B12 leading to B12 deficiency. It can also affect the absorption of other micronutrients. Folate and iron being the most common.
If you have one autoimmune disorder you are more likely to develop others so lots of people with PA also develop autoimmune thyroid conditions.
Thyroid conditions can also affect gut transit and can also lead to problems absorbing micronutrients.
Diagnosing a B12 deficiency/absorption problem from a single serum B12 reading is extremely difficult because people sit at different points in the range and some people will even be okay below the range. Symptoms are important in diagnosis but the overlap with other conditions - including thyroid problems will make the use of symptoms difficult in your case. There is also a strong overlap between the symptoms of folate deficiency and B12 deficiency. Diagnosing a B12 deficiency/absorption problem is easier if you have a history of serum B12 measurements that show a downward trend, or two measures that show a significant drop (ie a drop that it outside the variation that you would get from repeating a test several times on the same standard). Variation with serum B12 is 20% - variation with active B12 (which is what your results seem to be) would be much less.
Assuming that your diet is good and you are eating plenty of folate rich foods then your low folate levels would certainly indicate an absorption problem and if you have a folate absorption problem then the chances are that you also have a B12 absorption problem. In these instances it is recommended that the B12 deficiency is treated before the folate deficiency as there is a very small risk of SCDC.
PA is a long way from being the only B12 absorption problem - SIBO and H Pylori infection are also common causes of absorption problems and will affect other micronutrients. Whilst treatable both also have a high co-relation with PA.
The test for PA as a specific cause of B12 deficiency is IFAB (intrinsic factor antibody) but it isn't very sensitive so gives a false negative 60-40% of the time depending on the exact test methodology.
A test that is starting to be done instead is gastrin - a protein that controls release of stomach acidity and has been found to be extremely elevated in patients who have PA.
I agree, your reply is the simplest explanation I’ve read that presents the facts logically. It’s very difficult to explain and cover all scenarios without getting over complicated. Thanks!
Thankyou so much for such a detailed and informative response which has helped enormously in understanding this condition.
I believe my diet is pretty good, eating a well balanced and healthy diet the majority of the time so are concerned an absorption issue is going on whether it be a result of my thyroid condition or another issue.
I agree, the symptoms are confusing and are possibly overlapping and I had also assumed a lot of my symptoms were related to a Cardiac issue which has recently been resolved with a Pacemaker ie fatigue, weakness, breathlessness.
Will push for additional tests at the Gp surgery now I have all this info. Thankyou so much x
Low B12 and folate does not have to indicate Pernicious Anaemia, but in your case , with an autoimmune condition already it is indeed possible. Autoimmune conditions rarely come alone . Veganism and strict vegetarianism can result in low b12 ( Vitamin B12 is only found in animal products )
The only ( imperfect ) test for PA is the Intrinsic Factor Antibody test , Symptoms are the best indicators of PA . PA must be treated with B12 injections lifelong - . not tablets .
If it's not related to your diet, I would expect your GP to at least test you for PA (Pernicious Anaemia) and Coeliac disease, both autoimmune conditions that can lead to B12 deficiency.
Some links I post may have details that could be upsetting to read.
Link about What to do next if B12 deficiency is suspected or just diagnosed.
Sadly many of us have met doctors and other health professionals whose understanding of B12 deficiency and PA is limited. This sometimes means that people struggle to get a diagnosis and adequate treatment.
I think it's wise to read about B12 deficiency in case you meet one like that.
UK B12 documents
Search online for these when you have the time and energy
1) NICE B12 deficiency guideline - published March 2024
I have reservations about parts of this document. I feel there's too much emphasis on giving high dose oral B12 tablets as an alternative to B12 injections.
B12 injections are cheap but nurses' time to give them isn't. Oral B12 did not work for me, only B12 injections made a real difference.
2) NICE CKS Anaemia - B12 and folate deficiency - published a few years ago
3) BSH Cobalamin and Folate guidelines - published 2014
4) Try to find the local B12 deficiency guidelines your ICB (Integrated Care Board) in England is using. Health Boards in Wales/Scotland.
If you can't find them online, best bet is to submit a FOI (Freedom of Information) request to ICB or Health Board asking which B12 deficiency guidelines they are using and for a link to or copy of them.
As you have both B12 deficiency and folate deficiency.....
Is your GP aware that treating the folate deficiency without treating a co-existing B12 deficiency may lead to neurological problems. B12 treatment should be started first.
What treatment have you been given so far
for B12 deficiency ?
for folate deficiency?
"I was advised to have B12, Vitamin D, Folate and Ferritin levels checked "
Many on here report deficiencies in these.
I hope that GP tests Full Blood Count (FBC).
I also hope that they order a full set of iron tests not just ferritin.
It can be difficult to understand FBC results if someone has all three deficiencies - B12, folate and iron.
B12 deficiency ( and/or folate deficiency) may lead to red blood cells that are larger than normal (macrocytosis).
Iron deficiency may lead to red blood cells that are smaller than normal (microcytosis).
A person who has B12 deficiency (and/or folate deficiency) with iron deficiency, may appear to have red blood cells that are normal sized on FBC due to effects of iron deficiency masking effects of B12 deficiency (and/or folate deficiency).
I left detailed replies in the thread below eg book suggestions, symptoms lists, lists of causes, useful articles to pass to GP, links for those in UK having difficult health experiences with B12 deficiency
"I had also assumed a lot of my symptoms were related to a Cardiac issue which has recently been resolved with a Pacemaker ie fatigue, weakness, breathlessness."
B12 deficiency can be associated with some cardiac symptoms eg
palpitations
tachycardia
shortness of breath
chest pain
and others
Search for "B12 deficiency cardiac symptoms" for more info.
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Very high B12 but low folate 
Testing B12 and Pernicious Anaemia
Active B12 of 31.5, folate of 1.72 - missing periods?
